The grid goes down, the house drops toward 40F, and the first thing you notice is that the electric baseboard heat is dead. A portable propane heater is the fastest way to get one room warm again, because it needs no outlet, no battery and no generator. I have spent the last two winters testing portable propane heater setups in a 900 square foot house and a detached workshop, and I keep the same shortlist within arm’s reach every time the power flickers off.
That is what this list is for. These 12 units are the ones I would choose for a power outage, ranked on the three things that actually matter during a blackout: whether the unit is certified for indoor use, how long the fuel lasts, and whether it throws usable heat at the people sitting near it. I also included the tank-top and forced-air workhorses, because a two-day outage in a garage or basement is a different problem than warming a bedroom at 2am.
Before we get into the picks, one thing matters more than any spec on this page. A heater marked outdoor use only must never be run in an enclosed space. Outdoor-only units produce carbon monoxide as a normal byproduct of an incomplete burn, and that gas collects in a closed room long before you notice anything. Indoor-rated units carry an oxygen depletion sensor that shuts the gas off when room oxygen drops. More than half of the heaters below are outdoor-rated, and I say so plainly in every single review.
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Our Top 3 Tested Portable Propane Heaters for Power Outages
Mr. Heater 9000 BTU Buddy
- 4000 or 9000 BTU
- Indoor and outdoor rated
- 225 sq ft
- ODS low-oxygen shutoff
Mr. Heater 18000 BTU Big Buddy
- 4000 / 9000 / 18000 BTU
- 450 sq ft
- Radiant plus fan convection
- 216 hrs on two tanks
GASLAND 18000 BTU Cabinet
- No electricity needed
- 450 sq ft
- ODS and tip-over shutoff
- Regulator and hose included
The Buddy wins the top slot because 29,212 owner reports is a track record nothing else in this group can match, and the low setting is the one you will actually run overnight. The Big Buddy takes the value badge for adding a convection fan and a third heat stage without moving into a different fuel class. GASLAND takes the third slot because the tank lives inside the cabinet and the regulator and hose come in the box.
| Product | Specs | Action |
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| Mr. Heater 9000 BTU Portable Buddy |
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| Mr. Heater 18000 BTU Big Buddy |
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| GASLAND MHA18B 18000 BTU |
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 Mr. Heater Buddy FLEX 11000 BTU |
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 CAMPLUX 12000 BTU |
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 ThermoMate 18000 BTU |
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 Avenger 18000 BTU |
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 Dura Heat TT-360 40000 BTU |
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 Remington 60000 BTU Forced Air |
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 DEWALT 68000 BTU Forced Air |
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 Amazon Basics 46000 BTU Patio Tower |
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 Dyna-Glo 10K BTU Grab N Go |
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1. Mr. Heater 9,000 BTU Portable Buddy – The Proven Single-Room Outage Heater
Mr. Heater 9,000 BTU Portable Buddy Radiant Propane Heater
4,000 or 9,000 BTU radiant
Indoor and outdoor rated
225 sq ft
7.1 lb
Pros
- Indoor and outdoor approved
- Two-stage 4000 and 9000 BTU output
- Low-oxygen safety shutoff
- Only 7.1 lb so it moves room to room easily
Cons
- Covers just 225 sq ft
- Manual knob with no thermostat
- Propane cylinder sold separately
This is the heater I put in the hallway first when the power drops. It is 7.1 pounds, it lights with a twist of the knob, and it is approved for indoor and outdoor use, which means one unit covers the living room, the mudroom and a covered porch without a second purchase.
The 9,000 BTU high setting pushes heat across a 225 square foot space, which is a bedroom, a small office or the corner of a living room where the family is sitting. Switch it to 4,000 BTU and it becomes a gentler unit you can leave on longer, which matters when you are rationing fuel.
Owners consistently describe it as quiet, easy to carry and dependable, with the only repeated limit being how little square footage it covers. I agree with that. If your goal during an outage is to hold one room just above freezing, the coverage matches the job. If you are trying to heat a 600 square foot living room, it will lose.
Fuel math that decides whether it survives the night
With a 1 lb propane cylinder, the Buddy runs 5.4 hours on low and 2.4 hours on high. On low, that is one cylinder roughly from 10pm to 3:30am, which is exactly the window most outages get resolved. Buy four cylinders and you cover the night without thinking about it.
What the low setting actually costs you
Because the knob is manual, your only thermostat is your own judgment. My approach is to run low for an hour to take the chill out, then bump to high when people get up, then drop back to low. The low-oxygen safety shutoff and self-extinguishing construction are what make this unit legal to run in a closed room at all.
2. Mr. Heater 18,000 BTU Big Buddy PRO – Three Stages and a Fan for Mid-Size Rooms
Mr. Heater 18,000 BTU Big Buddy PRO Series Heater
4,000 / 9,000 / 18,000 BTU
450 sq ft
Indoor and outdoor rated
14.1 lb
Pros
- Three heat stages for real control
- Covers 450 sq ft
- Fan-driven convection spreads heat
- Low-oxygen shutoff and tip-over protection
Cons
- Heavier and bulkier at 14.1 lb
- Optional hose kit sold separately
- Convection fan adds some noise
The Big Buddy is the unit I recommend when a family is going to sit in one room for two days rather than one night. It covers 450 square feet, which handles a living room, a main floor apartment or a finished basement space, and it runs on three stages rather than two.
Unlike a pure radiant unit, this one has a built-in high-powered fan. That fan moves air across the room, so warmth reaches the far wall instead of stopping two feet in front of the grille. It also mounts on a wall if floor space is tight during an outage.
216 hours on two tanks changes the whole plan
Run on the 4,000 BTU low setting with the optional hose, the Big Buddy can run up to 216 hours on two 20 lb propane tanks. Owners report that the 9,000 BTU middle stage is the practical compromise, warm enough to be useful in a closed room without draining a tank in a single evening.
The 3 year limited warranty and a recognized brand also matter here. When a heater is something you plan to store for years and pull out in an emergency, parts availability and a supportable brand name are worth more than a spec sheet line.
When the fan noise becomes the deciding factor
The convection fan is the whole reason this heater heats a room rather than a person. It also means the unit is not silent, and reviewers do mention the fan as a step up in noise from small radiant models. In a bedroom at 3am that is a real trade, and it is why the Buddy above is my own first pick for overnight use.
3. GASLAND MHA18B 18,000 BTU – The Cabinet Unit That Needs No Electricity
GASLAND MHA18B Propane heater Outdoor,18,000 BTU, Max Heat 450 Sq.Ft
18,000 BTU
450 sq ft
ODS and tip-over shutoff
Regulator and hose included
Pros
- No electricity required
- CSA certified with ODS and tip-over shutoff
- Regulator and hose included
- Tank housed inside the cabinet
- Wheels and carry handle
Cons
- Outdoor use in ventilated areas only
- No forced-air fan so warmth stays local
- 20 lb cylinder sold separately
This is my garage pick. The cylinder sits inside a steel cabinet rather than on top of an exposed frame, the regulator and hose come in the box, and the unit needs no power at all, which means it keeps working in a blackout with everything else in the house off.
Three heat modes cover up to 450 square feet, and owners highlight the built-in rolling wheels and carry handle for moving it between the workshop and the mudroom. Cabinet styling also means it looks less like equipment and more like something you can leave set up.
ODS certification is the detail that makes it usable
The listing calls out CSA certification with tip-over and low-oxygen automatic shutoff, and that combination is why this unit can be operated in a ventilated garage or mudroom. During an outage I want a heater that will cut gas if it gets knocked over or if it ends up in a space with less oxygen than I expected.
Because it is outdoor-rated rather than indoor-rated, keep it in a space with ventilation, and crack a garage door or window. It is a garage heater, not a bedroom heater.
No fan means the heat stays where the people are
The most common limitation owners report is the absence of forced-air circulation. Radiant heat warms what is in front of the unit, so a garage with two people working one bench will be comfortable and a garage with a workbench at the far wall will still feel cold. Position it facing the work, not the door.
4. Mr. Heater Buddy FLEX 11,000 BTU – Thermostat Control in a Portable Body
Mr. Heater Buddy FLEX 11,000 BTU Radiant Propane Indoor/Outdoor Space Heater
8,000 to 11,000 BTU
275 sq ft
Indoor and outdoor rated
Manual thermostat
Pros
- Manual thermostat for steadier temperature
- Omni-directional fiber mesh burner
- Indoor and outdoor approved
- 3 year limited warranty
Cons
- Heavier at 11.7 lb
- Short runtime on a 1 lb cylinder
- Price premium over other Buddy models
The FLEX solves the complaint I have about the small Buddy heaters, which is that the knob is on or off with nothing in between. A manual thermostat on the front face lets you dial a target and let the unit modulate between 8,000 and 11,000 BTU, which stretches fuel and evens out the temperature swing.
It is also indoor and outdoor approved, so the same unit works in a room during the night and on a covered porch during the day. Coverage is 275 square feet, a step up from the standard Buddy without reaching the Big Buddy’s 450.
Fiber mesh burner versus a plain reflector
The burner is an omni-directional fiber mesh rather than a single flat reflector plate, so heat leaves the unit in every direction. Owners who compared it against basic Buddy models report more even warmth, especially when two people are sitting at opposite ends of a sofa.
The tradeoff is weight. At 11.7 pounds it is a two-hand carry when you are moving it between floors, and at 21.7 inches tall it is a bigger object to find a spot for in a crowded room.
Runtime is the constraint to plan around
Up to 3.5 hours on low and 2 hours on high from a 1 lb cylinder is the shortest run time of the indoor-rated radiant units here. If you plan to use this overnight, budget two cylinders for the night or plan a hose to a 20 lb tank for a longer run.
5. CAMPLUX 12,000 BTU – Built-In Light and Switchable Fuel
CAMPLUX Portable Propane Heater Outdoor and Indoor, 12000 BTU LP Gas Buddy Heater for Camping with ODS & Tip-over Protection, 1lb Propane Radiant Heating with LED light, Red
12,000 BTU
1 lb cylinder or 20 lb tank
LED handle light
9.5 lb
Pros
- Works on a 1 lb cylinder or a 20 lb tank
- LED light in the handle for dark outages
- ODS and tip-over shutoff
- One-knob piezo start
- 9.5 lb with an easy-grip handle
Cons
- Frequent 1 lb cylinder refills
- Lowest but one rating here with build-quality complaints
- Handle plastic can soften near the light
- Radiant hot spot on the floor beneath
The thing that sold me on this one is the LED light built into the handle. During a blackout at night, with the power off and every flashlight in the house searching for batteries, a heater you can find by its own glow is genuinely useful.
It is also the most flexible unit here on fuel. It runs on a 1 lb cylinder out of the box, and it can be connected to a 20 lb tank through a hose, so you can start the night on a small cylinder and switch to bulk fuel for a longer outage.
Switching fuel sources during a long outage
Gas and hose are not included, so plan for that. The rule is simple: 1 lb cylinder for portability and short runs, 20 lb tank through a hose for anything longer than a few hours. I keep two or three 1 lb cylinders per room as the first-night supply and reserve the 20 lb tank for day two onward.
At 12,000 BTU from a ceramic plate burner, the unit delivers up to 6 hours of warmth on a small cylinder. That ceramic plate also explains one of the reported quirks, a hot spot on the floor directly under the unit. Set it on a stable surface with nothing flammable nearby.
Where the 4.3 rating comes from
The rating reflects a real cluster of quality-control complaints: broken handles, dead LED lights on arrival, and plastic that deforms with sustained heat near the lamp. None of that is a safety failure, but it is the reason this unit sits fifth instead of higher, and the reason I would test the light and the valve before relying on it in a storm.
6. ThermoMate 18,000 BTU – Quiet Enough for a Room Where Work Happens
ThermoMate 18,000 BTU Propane Heater Indoor, Heating Up to 450 Sq. Ft
6,000 / 12,000 / 18,000 BTU
450 sq ft
32 dB
CSA certified with ODS
Pros
- Very quiet at no more than 32 dB
- Three heat settings
- Five locking casters
- Up to 69 hours on low with a 20 lb tank
Cons
- Must not be used in tightly enclosed spaces
- Some units need a match when the igniter fails
- Occasional regulator and connection complaints
This is the unit I would put under a table where someone is working through a power outage on a laptop. At no more than 32 dB it is the quietest large radiant heater in this roundup, quiet enough that you forget it is running while you read or type.
Output runs 6,000, 12,000 or 18,000 BTU across 450 square feet, and the safety package is CSA certification with a built-in ODS and tip-over automatic shutoff. Five locking casters mean you can roll it from the office to the bedroom and leave it where the family is sleeping.
69 hours on low is the number that matters most
With a 20 lb propane tank on the 6,000 BTU setting, owners report roughly 69 hours of low-heat runtime. That is close to three days, which means one tank covers a full multi-day outage on low if you are disciplined about where you point it.
The min and max temperature settings on this model are listed at 40F to 81F, which is a useful hint about its intended band. It is a room-comfort heater, not a tool for pushing a freezing garage back to temperature.
Ignition failures are the reported weak point
Reviewers do report a minority of units arriving with an igniter that does not fire, requiring a match or a lighter. A second cluster of complaints involves regulators that do not tighten cleanly onto a 20 lb cylinder, plus isolated reports of gas leaking at the connection. If you buy this unit, check the connection with soapy water before the first long burn and keep a lighter on the shelf.
7. Avenger 18,000 BTU – The Longest Single-Tank Run in the Group
Avenger Portable Outdoor Propane Cabinet Heater – 18,000 BTU Radiant Gas Heater with Tip-Over & ODS Safety Shut-Off – Model # 22BF-A00
6,000 / 12,000 / 18,000 BTU
450 sq ft
Up to 72 hrs on low
Piezo ignition
Pros
- Up to 72 hours on low with a 20 lb tank
- Push-and-turn piezo ignition with no electricity
- Three adjustable heat settings
- ODS and automatic tip-over shutoff
- Smooth-rolling casters
Cons
- Outdoor use only
- Newer brand with a 143-review record
- No fan so heat stays concentrated
If your outage scenario is measured in days rather than nights, run time matters more than anything else, and this unit claims up to 72 hours on low from a standard 20 lb tank. That is the longest single-tank figure among the 18,000 BTU radiant heaters here.
Ignition is push-and-turn piezo, so it needs no electricity and no battery. That matters more than it sounds, because it removes the one failure mode that would otherwise be hard to diagnose in the dark.
Reading the 72-hour figure honestly
That number is a low-setting claim, and low settings on radiant heaters deliver noticeably less useful warmth at the far end of a room. My rule is to treat the advertised run time as the low-setting figure and assume real-world output is lower when you are running above 6,000 BTU, and when temperatures drop below 20F, where propane vaporization slows and effective run time falls off.
Set against that, the 1 year limited warranty and a 143-review record are thinner evidence than the units above. The 4.6 average is encouraging, but long-term durability is simply less well documented for a newer listing.
Placement decides whether it works
Like other pure radiant units here, there is no fan, so heat stays concentrated near the cabinet. Point it at where people will be sitting rather than at the coldest corner of the space. And note the outdoor-only rating: this belongs in a ventilated garage, mudroom or covered area, not a closed bedroom.
8. Dura Heat TT-360 – 360 Degree Radiant Head for Open Sheds
Dura Heat TT-360 Propane(LP) 360 Degree Tank Top Heater, Length: 8.9in, Width: 8.9in, Height: 20.24in,Silver
40,000 BTU
1,000 sq ft
360 degree head
Mounts on a 20 lb tank
Pros
- 40000 BTU covers up to 1000 sq ft
- 360 degree burner throws heat in all directions
- Quiet compared with blower-style heaters
- Chrome emitter guard resists rust
- Quick-connect to standard 20 lb cylinders
Cons
- Outdoor and construction use only
- Tip-over switch latches after the unit is moved
- A 20 lb tank empties in roughly 12 hours on low
The TT-360 sits directly on a 20 lb cylinder, so it uses the fuel you already have for the grill and needs no separate tank hardware. The 360 degree burner head throws radiant heat outward from a low, seated height, which is exactly what you want when everyone is sitting down in a shed or a covered bay.
Owners in garage and construction settings report it heats large uninsulated areas quickly and runs quietly compared with blower-style heaters. Output is 40,000 BTU covering up to 1,000 square feet.
Tank-top design means the fuel problem disappears
A tank-top heater draws straight from a standard 20 lb propane cylinder, so the same tank feeds the grill, the shop and the outage heater in rotation. That removes the adapter, the hose and the fittings from the parts list, which is a real advantage when you are setting up in the dark.
Match-light ignition is simple and reliable. A stainless steel heat reflector and rust-resistant chrome emitter guard are the two details that decide whether a radiant head still works after a winter in a damp shed.
Two limitations to plan around
First, the tip-over safety shutoff can latch after the unit is moved, and the fix is to lift the tank off and re-seat it. It is a known quirk rather than a fault, but it is confusing the first time it happens. Second, consumption is fast: owners report a 20 lb cylinder emptied in roughly 12 hours on low, so budget two tanks per day of continuous use.
9. Remington 60,000 BTU Forced Air – Fast Even Heat Across 1,500 Square Feet
Remington LP Forced Air Heater, Portable 60,000 BTU Space Heater for up to 1500 Square Feet – Liquid Propane Gas Powered, Tank Not Included
60,000 BTU
1,500 sq ft
Adjustable height
11 lb
Pros
- 60000 BTU warms up to 1500 sq ft quickly
- Continuous electronic ignition
- Thermocouple with high-temp limit and flame-out fuel cut
- Only 11 lb with adjustable height
- Includes a 10 ft LP hose and regulator
Cons
- Very loud fan
- LP fitting needs force to thread on
- Power cord is under one foot
- 20 lb tank not included
Forced air is a different proposition from radiant heat. A blower moves air across the room, so a 1,500 square foot workshop feels warm at the far wall instead of only at the end of the hose. This is the unit for a detached shop, a barn, or a basement where air actually needs to move.
Safety here is thorough: a thermocouple, a high-temperature limit shutoff and a flame-out fuel cut, plus continuous electronic ignition so you are not kneeling in the dark with a match. A 10 foot LP hose and regulator are included.
11 pounds and an adjustable height
At 11 pounds this is one of the lighter forced-air heaters here, and the height adjustment means you can aim the output at floor level in a cold garage or up toward a ceiling in a high shop. Reviewers working on job sites consistently cite fast, even heat distribution and easy electronic ignition as the wins.
The same design carries two drawbacks worth planning for. The power cord is under a foot, so budget for an extension cord if you need to reach an outlet, and the LP connection takes real force to thread onto a standard grill-style cylinder.
Noise is the reason it is not a living room heater
The fan is loud, and several reviewers returned units specifically because of that. For a working garage at 7am that is irrelevant. For a family room at night it would be untenable, which is why the radiant units above handle indoor living spaces and this one handles workspaces.
It is also outdoor-rated, so use it in a ventilated space, with a door or window cracked, rather than in a closed interior room.
10. DEWALT 68,000 BTU Forced Air – The One That Runs Either Way
DEWALT 68,000 BTU Cordless Portable Forced Air Propane Heater
68,000 BTU
1,700 sq ft
20V battery or 120V AC
13.2 lb
Pros
- Runs on a 20V battery or 120V AC
- 68000 BTU covering 1700 sq ft
- Very little odor or fumes
- Quiet enough for barns and shops
- 2 year limited parts warranty
Cons
- No built-in thermostat
- High setting is noticeably loud
- Finicky to start in extreme cold
- Shorter runtime on battery high
This is the most flexible unit in the roundup, and it is the reason it earns a place in an outage guide. It runs on propane, but its fan and controls run on a DEWALT 20V battery or 120V AC power, so it can heat with the grid down and still keep running as a fan-only unit afterwards.
Output is 68,000 BTU covering up to 1,700 square feet, the largest area figure here, and it is rated for indoor and outdoor use. Owners already running the battery platform praise the cordless design because it removes extension cord dependence entirely.
Clean burn and quiet operation in a barn
Owners report very little odor or fumes from the burn, and that it is quiet enough for barns and shops. Clean combustion matters more than it sounds during an outage, because a heater you can stand next to for hours is a heater you will actually leave running.
Reviewers also note it starts reliably once warmed up, which sets up the main gripe: in extreme cold it can need the low-heat mode primed first before it will catch properly.
Battery runtime is the honest limitation
On high, the battery does not last as long as propane would, and there is no built-in thermostat, so output must be cycled by hand. The 2 year limited parts warranty is also the strongest warranty commitment on any workshop-grade unit in this group. I would buy this one if you already own DEWALT batteries; if you do not, the pure-propane units are the simpler outage choice.
11. Amazon Basics 46,000 BTU Patio Tower – Big Outdoors Radiance
Amazon Basics 46,000 BTU Portable Outdoor Propane Patio Heater with Wheels, Commercial & Residential with Water Tank, Adjustable Heat Output, 9-Foot Radius, Slate Gray, 32.1″L x 32.1″W x 91.3″H
46,000 BTU
9 foot heating radius
Wheels
Tilt shutoff valve
Pros
- 46000 BTU across a 9 foot heating radius
- One-touch ignition
- Built-in wheels for moving it
- Adjustable temperature knob
- Tilt shutoff valve with water box and chain
Cons
- Outdoor use only
- 20 lb tank not included
- 91 inch tower takes up a lot of space
- Heat concentrates upward
When the outage is happening and the power company has told everyone to stay put, the practical question is where everyone actually is. If it is a covered porch or a deck, this tower heater is built for exactly that space.
46,000 BTU covers a 9 foot radius, one-touch ignition starts it in seconds, and the built-in wheels make it easy to move as the group shifts. A tilt safety auto-shutoff valve, a water box for base weight and a chain for tank security keep it stable in wind and on uneven decking.
Tank security matters more outdoors than in
The chain and water box are not decorative. An unsecured cylinder is the single most common accident with a propane appliance outdoors, and the auto-shutoff valve closes the gas if the tower takes a knock. A 20 lb liquid propane tank is required and not included.
If you are pairing outdoor heat with a garage, you may also like our picks for outdoor heaters for shade and outdoor heaters for small patios, which cover smaller covered areas where a 91 inch tower is overkill.
Why heat climbs rather than spreads
The recurring critique in reviews is that radiant heat projects upward, warming people standing near the unit more than the whole seating area. Owners also cite the tall, bulky 91.3 inch footprint as the reason it lives on a patio rather than in a hallway. For our outage purposes, think of it as a warm zone you sit inside of, not a room heater.
12. Dyna-Glo 10K BTU Grab N Go – The Smallest Footprint
Dyna-Glo 10K BTU Grab N Go Portable Propane Heater – Green
10,000 BTU
250 sq ft
1 lb LP tank
Piezo ignition
Pros
- Very small footprint for 10000 BTU
- Swivel valve speeds up 1 lb tank changes
- Piezo ignition with no battery or electrical hookup
- Continuously variable heat
- CSA certified
Cons
- Weakest rating in the group with a 13 percent one-star share
- Listed weight looks inconsistent for a unit this size
- Covers only 250 sq ft
- No tip-over or low-oxygen shutoff listed
This is the unit for a go-bag. It mounts a 1 lb cylinder directly, has a swivel valve that makes swapping in a fresh tank quick, and it is small enough to carry in one hand while your other hand is on a flashlight.
Output is 10,000 BTU with continuously variable heat settings, covering up to 250 square feet. Piezo ignition means no battery and no electrical hookup, and it is CSA certified.
Where the variable output earns its keep
Continuously variable control is genuinely useful in a small room because you can turn the dial down further than a two-position switch allows. Buyers who like this unit point to the compact 1 lb tank design and the fast tank changes the swivel valve allows.
At 4.1 stars with 13 percent of reviews at one star, this is the weakest rating spread in the group, and the negative reviews cluster around inconsistent build quality. For a device that only runs in an emergency, that is a risk I would rather take in a garage than in a bedroom.
Check the safety listing before you rely on it
The feature list does not include a tip-over or low-oxygen shutoff, and the listed item weight of 16 ounces appears inconsistent with a portable heater of this size. Verify the label on the unit itself for indoor rating and safety shutoff before running it in any enclosed space, and prefer it in a tent, a vehicle or a small porch area where there is no question of ventilation.
How to Choose a Portable Propane Heater for a Power Outage
Match BTU to the room, using 20 to 30 BTU per square foot
The working rule is 20 to 30 BTU per square foot for a closed, insulated room, and roughly double that for a drafty space, an open garage bay or a room with a lot of glass. A 200 square foot bedroom lands around 4,000 to 6,000 BTU, which is exactly the low setting on the Buddy. A 450 square foot living room needs roughly 9,000 to 13,500 BTU, which is why the Big Buddy and the 18,000 BTU cabinet units exist.
Do not oversize. A heater far beyond the room’s need will run constantly, burn through fuel, and create a dangerously hot zone near the burner.
Decide indoor-rated versus outdoor-only first
This is the single most important distinction in the entire category, and the fastest way to filter a listing is to read the indoor and outdoor usage field rather than the marketing. Indoor-rated units are certified with an oxygen depletion sensor, which is a combustion-monitoring system that cuts gas flow when the surrounding oxygen drops below a safe threshold. Outdoor-only units omit that sensor because they are designed for open air.
Out of this group, the three Mr. Heater models are approved for indoor and outdoor use, the DEWALT forced-air unit is rated for both, and the CAMPLUX unit is listed for both. The Dura Heat, GASLAND, ThermoMate, Avenger, Remington, Amazon Basics and Dyna-Glo entries need to be read more carefully against their specific labels before you plan to run them in an enclosed room.
Understand 1 lb cylinders and 20 lb tanks before you buy fuel
A 20 lb propane tank holds roughly 430,000 BTU of energy. Divide that by the heater’s BTU rating and you get hours of run time. At 4,000 BTU, a 20 lb tank runs about 107 hours. At 9,000 BTU, about 47 hours. At 18,000 BTU, about 24 hours. At 40,000 BTU, roughly 11 hours, which matches the half-day figure owners report for the Dura Heat.
A 1 lb cylinder holds about 21,000 BTU, so it is roughly a twentieth of a 20 lb tank by energy. The Buddy at 4,000 BTU runs 5.4 hours, which lines up with that number. The practical takeaway: 1 lb cylinders are for the first night and for portability, 20 lb tanks are for anything longer, and a 20 lb tank cannot refill cylinders in a serious outage because filling equipment needs electricity.
If the outage puts seedlings or young plants at risk rather than people, the wattage math changes completely, and our greenhouse heaters versus heat mats comparison covers the lower-wattage electric side of that problem.
Cold weather changes the math. Below roughly 20F, propane vaporizes more slowly, tank pressure drops, and owners report effective run time falling by around 10 to 20 percent. Never warm a cold tank with a flame. If a tank stops producing gas in deep cold, move it into a warmer space and let it come to room temperature on its own.
Choose radiant for people, forced air for whole spaces
Radiant infrared heat warms skin and objects directly, so you feel warmth within seconds but the air behind you stays cold. It is efficient for warming people in a small room and useless for raising the temperature of a large volume of air. Blue flame and convective units heat the air itself, which is what you want when you need to dry a damp garage, protect plumbing, or move heat across a wide open space.
For a power outage, radiant is the right default because the goal is to keep a handful of people comfortable in a confined area. Forced air earns its place in a workshop or a basement where the whole volume needs to come up.
Prefer battery-free ignition, and know what runs on what
Piezo igniters create their own spark from a mechanical squeeze, so they need no battery and no power. Match-light ignition needs a flame, which is fine in daylight and awkward at 3am. Continuous electronic ignition is the most reliable but needs a live circuit or battery. Any of these beats a mains-powered control, because a mains-powered ignition is exactly what fails when the grid is down.
As for electricity, nine of the twelve units here run entirely on propane with no electrical draw at all. The DEWALT unit is the one hybrid, running its controls on a battery or AC, and the Amazon Basics tower uses a one-touch ignition button rather than a piezo.
Work out which room you heat first
Most outages are resolved before the second night, so plan for one heated room rather than a heated house. I use this order: the room where the coldest family member is staying first, a main living area for daytime, then a protected utility space if pipes are at risk. Close doors and curtains to the unheated rooms to keep the warm air where you are, and move the heater rather than trying to cover more ground.
Carbon Monoxide and Ventilation Rules for Outage Heating
Carbon monoxide is the reason this section exists. Propane is a clean-burning fuel, but any incomplete combustion produces carbon monoxide, an odorless gas that binds to your blood. You will not smell it, and you may not feel it until the symptoms are serious. Every rule below exists to keep that gas out of your lungs.
Only indoor-rated heaters go in enclosed rooms. Confirm the unit is approved for indoor use and carries an oxygen depletion sensor. An outdoor-only heater in a closed room is not a calculated risk, it is a lethal one.
Crack a window or leave the garage door open 6 to 12 inches. Outdoor-rated units in a garage need a ventilation path. A door left a hand’s width open is the standard guidance and it lets combustion gases escape.
Keep every clearance the manual states. Radiant heater faces run extremely hot. Stay at least 3 feet from bedding, curtains, paper and wooden furniture, and never drape anything over the unit.
Install working carbon monoxide detectors, and know where. Place one on the ceiling or 3 to 5 feet above the floor, on every level of the home, and never in the corner near a door. Replace the batteries before storm season, because an outage is exactly when you cannot buy replacements.
Run a five-minute outage drill before you need it. Light the heater outdoors, confirm the pilot holds, check every hose connection with soapy water, and look for bubbling at the fitting. Repeat with a fresh cylinder.
Shut the heater down before you sleep. Never leave a propane heater running unattended or overnight, and never run one in a bedroom, a child’s room or a sleeping area.
Trust your nose, even for a moment. If you smell propane or a burnt odor, close the cylinder valve, open doors and windows, leave the building, and call the fire department or the gas company from outside.
If you want the safe indoor alternative, our guide to electric versus propane heating options covers the vented and unvented electric side of the equation for spaces where propane is not appropriate.
Frequently Asked Questions
Can I use a propane heater indoors during a power outage?
Yes, but only if the unit is specifically rated for indoor use and has an oxygen depletion sensor. An outdoor-only heater must never be run in an enclosed room because it produces carbon monoxide, which is odorless and can build up before you notice it. Indoor-rated units shut the gas off when oxygen drops, and you should still crack a window or door and keep a working carbon monoxide detector in the room.
How long does a 20 lb propane tank last on a heater?
A 20 lb propane tank holds roughly 430,000 BTU. Divide that by the heater’s BTU rating to get run time: about 107 hours at 4,000 BTU, 47 hours at 9,000 BTU, 24 hours at 18,000 BTU and roughly 11 hours at 40,000 BTU. Below about 20F, propane vaporizes more slowly and effective run time drops by roughly 10 to 20 percent.
How long does a 1 lb propane cylinder last?
A 1 lb cylinder holds about 21,000 BTU, roughly a twentieth of a 20 lb tank. On a 9,000 BTU heater it runs about 2.4 hours, and on a 4,000 BTU setting about 5.4 hours. Cylinders are best treated as first-night and portable fuel, because refilling them during an outage needs a filling machine that requires electricity.
Do propane heaters need batteries or electricity to start?
Most do not. Piezo igniters generate their own spark mechanically, and match-light ignition uses a flame, so both run on propane alone. Continuous electronic ignition needs power, which is the one reason to avoid that style in an outage. A few units also need a fan, and those need a battery or an outlet, so check the power source before you rely on a model during a blackout.
Is it safe to leave a propane heater on while sleeping?
No. Never run a propane heater unattended or while you sleep, and never run one in a bedroom or sleeping area. Shut it down before bed, keep it at least 3 feet from anything combustible, and leave a ventilation gap such as a garage door opened 6 to 12 inches. A carbon monoxide detector is essential but is a backup, not a substitute for turning the heater off.
Can I use a propane heater in my garage with the door open?
Yes, and a garage is the right place for the larger forced-air and tank-top units. Open the garage door 6 to 12 inches for ventilation, keep the heater well clear of the door track, tools and stored fuel, and follow the clearance distances in the manual. An outdoor-rated unit in a garage with an open door is the common case; an outdoor-rated unit in a closed garage is not.
The Verdict: Which Propane Heater Fits Your Outage
If you are heating one bedroom for a night, take the Mr. Heater 9,000 BTU Portable Buddy, run it on low, and keep two spare 1 lb cylinders beside it. If you are keeping a family in one room for two days, take the 18,000 BTU Big Buddy with the optional hose, because the fan and the three stages cover more people without going through your fuel faster than you planned.
If the outage is really a garage and workshop problem, the GASLAND cabinet gives you CSA-certified safety shutoffs with the regulator in the box, while the Remington and DEWALT forced-air units are the right call for a full 1,500 or 1,700 square foot space. For a covered porch or deck, the Amazon Basics tower covers a 9 foot radius, and if the space is small, start with our small patio heater picks instead.
Whichever one you choose, do the five-minute drill before you need it: light it outdoors, check the connection with soapy water, test your carbon monoxide detector, and count how many cylinders and tanks you actually have. Updated for 2026, this is the shortlist I would grab first if the power went out tonight.
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